(1) Field of the Invention
This invention relates to a pellicle having reflection-preventing function which is characterized as having an improved light transmission and which is used as a dust cover for a photomask or reticle at the light exposure lithography of a semiconductor.
(2) Description of the Related Art
A proposal has already been made and practiced in which a dust cover called "pellicle" is built in a photomask or reticle for the light exposure lithography of a semiconductor to prevent or minimize the loss at the light exposure lithography step by dusts and enhance the productivity. Nevertheless, to shorten the light exposure time for further enhancing the productivity, it becomes urgently required that the transmission of the light from an exposure source must be further increased. As the means for coping with this requirement, a method has been proposed in which a pellicle is combined with a reflection-preventing film (see Japanese Unexamined Patent Publications No. 60-237450, 61-53601, 61-209449, 1-191852, 1-191853 and 1-191854), and fluorine-containing resins having a low refractive index have been mainly used for the preparation of the reflectionpreventing film.
The conventional fluorine-containing resins for the reflection-preventing film has a low refractive index, but the transparency is not always satisfactory and a sufficient improvement of the light transmission is not attained. Moreover, the adhesion between the main film of the pellicle and the reflection-preventing film is not satifactory, and when the laminated pellicle film is peeled from a pellicle-formed substrate, there is a large risk of separation between the main film of the pellicle and the reflection-preventing film. Accordingly, a special contrivance must be made to the peeling method for peeling a pellicle having a laminate structure, resulting in disadvantageous reduction of the productivity. Furthermore, control of the quality is difficult.
As the means for overcoming these advantages, a method is desired for improving a poor adhesion of the fluorine-containing resin while utilizing most of merits of the fluorine-containing resin.